In a computing environment in which multiple guests share a common physical adapter of a host system, each guest may be assigned a respective virtual adapter for use in performing data input and output. Multiple guest operating systems, for instance, may share a physical host bus adapter (HBA), such as a physical fibre channel adapter, to provide connectivity to a network. A physical fibre channel adapter may include multiple virtual host bus adapters (HBAs), each dedicated for use by a respective guest. Typically, a guest will load, i.e. by a boot sequence or initial program load (IPL), into an operating system that will issue commands to bring up, or activate, a virtual adapter assigned to service the guest data input/output (I/O) requests. In channel I/O technologies, these commands are provided as a channel program of specialized instructions known as channel command words, or “CCWs”, to activate a virtual HBA on the shared physical channel adapter. The activated virtual HBA will be assigned unique identifiers and other configuration information. For instance, the activated virtual HBA will reach out to the network and request an identifier that uniquely identifies the virtual device within the network.
In large-scale fibre channel networks, endpoints that connect devices to a fabric are known as node ports (“N_ports”). In a storage area network (SAN), as one example, N_ports include ports of the storage devices in addition to the ports of the physical HBAs that access them. These are examples of physical N_ports, though N_ports may also be virtual. Virtual HBAs and other types of virtual adapters that communicate with network devices are termed virtual N_ports.
Both virtual and physical N_ports are assigned a fibre channel identifier (“N_port ID” or “fibre channel id”) to uniquely identify the N_port within the local fibre channel network. N_ports—both physical and virtual—login to the network and request the fibre channel id from the fabric. Further, a global unique identifier called a world wide port name (WWPN) is assigned by a system, such as a central electronics complex, of which the N_port is a part. Any host bus adapter, physical or virtual, within a fibre channel environment has an associated WWPN to uniquely identify that component within the environment. Additional configuration information may be assigned to host bus adapters within the environment, which may include hundreds of such host bus adapters and therefore an equally large number of unique HBA configurations.